W3 - Signalling (Sensory/motor)

Question 1

What afferent endings are responsible for converting energy of stimulus into an electrical signal?

Answer 1

Somatosensory afferents

Question 2

Once the cation channels open, what can the generator potential become if the threshold is reached?

Answer 2

Action potential (during depolarisation)

Question 3

What is particular about a-alpha or a-beta mechnaoreceptor endings?

Answer 3

They are encapsulated

Question 4

What are a-gamma and C nerve fibre endings called?

Answer 4

Free nerve endings

Question 5

Which afferents detect skin motion/grip and which detect edges/changes in texture?

Answer 5

1 - Meissner’s afferents, 2 - Merkel cell afferents

Question 6

What afferents detect skin stretch and which tetect vibrations?

Answer 6

1 - Ruffini afferents, 2 - Pacinian afferents

Question 7

What does two-point discrimination threshold measure?

Answer 7

Minimum interstimulus distance required to perceive two simultaneous stimuli individually

Question 8

What nerves are visceral afferents sent through?

Answer 8

Sympathetic nerves

Question 9

What is proprioception?

Answer 9

The understanding of where our body is in space and in relation to other parts of the body

Question 10

Where are proprioceptor mechanoreceptors found?

Answer 10

Muscles, tendons and joints

Question 11

Basal ganglia and cerebellum control complex movements/proprioception, is this true or false?

Answer 11

True

Question 12

What are 3 things proprioceptors detect?

Answer 12

Force of movement, muscle tension and muscle stretch

Question 13

What muscles do somatic innervation involve?

Answer 13

Skeletal muscles

Question 14

What do muscles do visceral innervation involve?

Answer 14

Smooth, cardiac (+ glands)

Question 15

What do large alpha motor neurons innervated and what do they facilitate?

Answer 15

Extrafusal skeletal muscle fibres, posture and movement

Question 16

What do small gamma motor neurons innervated and what do they facilitate?

Answer 16

Intrafusal muscle fibres ?????????????

Question 17

What does a motor unit consist of?

Answer 17

A motor neuron (usually alpha) and the muscle fibre(s) it innervates

Question 18

Why can one action potential cause all muscle fibres in one motor unit to contract?

Answer 18

Multiple muscle fibres are innervated by a single ventral horn alpha motor neuron

Question 19

What does the size of a motor unit depend on?

Answer 19

The number of muscle fibres innervated (smaller motor neurons innervate fewer)

Question 20

What is particular about the threshold for activation for smaller vs larger motor units?

Answer 20

Smaller motor units have a lower threshold, needing fewer ions to influx for an AP

Question 21

What are the 3 types of motor units?

Answer 21

Slow, fast fatigue resistant and fast fatigable

Question 22

What are slow motor units used for and when are they recruited?

Answer 22

Used for sustained contraction (standing) and recruited earlier

Question 23

When are FR motor units recruited?

Answer 23

After slow, before FF

Question 24

What activity would a FF motor unit be needed to be recruited for? An FF motor unit is recruited last

Answer 24

Short, fast bursts of movement such as for a sprint